The present invention relates to a display device of a matrix type such as a plasma display panel (PDP), a liquid crystal display (LCD), and an electroluminescent display (ELD) for displaying color images.
Recently, as a display device becomes large in size, thickness of the display device is desired to be thin. Therefore, various types of display devices thin are supplied. In the display device such as PDP, LCD and ELD, three primary colors of red (R), green (G) and blue (B) are properly combined to display various color images. In the matrix display, three unit luminous areas corresponding to the three primary colors are provided in each pixel. As one of the matrix type display devices in which color images are properly displayed using a phosphor layer, a PDP of a surface discharge type using alternating current (AC) is known.
For example, a PDP of surface discharge type of three-electrode comprises a pair of front and rear substrates disposed opposite to each other, interposing a discharge space therebetween. The front substrate as a display portion has a plurality of row electrodes which are alternately disposed in pairs to be parallel with each other at the inside portion thereof. The row electrodes are covered by a dielectric layer at the discharge space. On the rear substrate, a plurality of column electrodes are formed on the inside portion thereof to intersect the row electrodes of the front substrate. A phosphor layer having a different luminous color covers each of the column electrodes. At the intersection of each of the column electrodes and each pair of row electrodes, a unit luminous area (discharge cell) is formed.
FIG. 3 shows an arrangement of pixels in the conventional PDP of surface discharge type.
A pair of row electrodes X and Y are laterally disposed, interposing a discharge gap at every line L as a display line. A plurality of column electrodes A (Ai, Ai+1, Ai+2 . . . ) are disposed to intersect the row electrodes X and Y. A plurality of phosphor layers 8 (8R, 8G and 8B) are provided on the column electrodes A. The phosphor layers 8R, 8G and 8B have luminous colors red (R), green (G) and blue (B) respectively, corresponding to the three primary colors R, G and B. The phosphor layers 8R, 8G and 8B are disposed on the column electrodes A in the order from the left to right in FIG. 3.
At the intersection of the data electrode A having the phosphor layer 8 and the row electrodes X and Y, a unit luminous area EU is defined. Corresponding to the luminous colors of the phosphor layers 8B, 8G and 8B, a unit luminous area EU(R) of red (R), a unit luminous area EU(G) of green (G), and a unit luminous area EU(B) of blue (B) are respectively defined.
A pixel EG consists of three unit luminous areas EU(R), EU(G) and EU(B) which are disposed in the order from the left to right in FIG. 3.
In a driving operation of the PDP, a unit period of display is divided into an address period and a discharge sustaining period.
In the address period, pixel data pulses are applied to the column electrodes, while scanning pulses are applied to one of the row electrodes by a selecting and writing address method or a selecting and erasing address method. Thus, a wall charge is accumulated only in the unit luminous area EU to be lighted every line in order.
In the discharge sustaining period, discharge sustaining pulses are alternately applied to the row electrodes X and Y. Thus, only the unit luminous area EU to be lighted which holds the wall charge sustains the discharge. If the number of applications of discharge sustaining pulses per unit time is properly set, the luminance of the display can be controlled.
In the address period, if a difference of potential is produced between the column electrodes, a reactive power produces by a parasitic capacitance between the data electrodes. In particular, in case of a monochromatic display by either of R, G or B, the reactive power increases. For example, in the monochromatic display of R, a parasitic capacitance between the column electrode of R and the column electrode of G adjacent to the column electrode of R, and a parasitic capacitance between the column electrode of R and the column electrode of B adjacent to the data electrode of R are equivalently loaded, thereby increasing the reactive power.
In order to reduce the parasitic capacitance between the column electrodes which causes the reactive power to increase, it is necessary to provide a sufficient large distance between the column electrodes. Therefore, it is difficult to obtain the PDP of high definition by reducing the distance between the column electrodes.